When the low SOC control request is output and the catalyst warming request is not output, the low SOC control mode is set as a control mode and the state of charge (SOC) of the battery is controlled according to the managing center SOC* set as the smaller value S2 than the value S1 for the normal time. When the catalyst warming request is output, the catalyst warming mode is set as a control mode regardless of the low SOC control request and the engine is controlled to perform the self sustained operation (no-load operation) at the idling rotation speed Nidl with the spark-retard state. Namely, when the battery temperature is low and the catalyst temperature is also low, the catalyst warm-up is given a higher priority than the low SOC control and prevents the exhaust emission from becoming worse.